Explosion tubbinb



Patented Apr. 4, I933 UNITED STATES PATENT OFFICE HOIIZ'WABTH, OI"D'USSELDOBI' GERMANY, ASSIGNOB TQ HOLZWAB'IE GAB TURBINE 00., OF SANFRANCISCO, CALIFORNIA, A OOBPORLTION O! DELAWARE EXPLOSION TURBINEApplication filed Iebruu'y 8, 1929, Serial 10.

by means of coal dust, and more particularly but a continuous turbine 0for effecting self-ignition of a coal dust and air mixture in theexplosion chambers of such turbine.

Among the known internal combustion engines designed to employ coal dustas a fuel, those which effect ignition of the fuel in ,a manner similarto the Diesel process, that is, by injectin the coal dust into a body ofhot compresse air in the combustion chamber, appear to have led to thefirst practical success; on the other hand, ordinary piston engines havenot yet'been operated successfully with coal dust and air underself-ignition of the mixture. Many attempts have been made to efiect thecombustion of coaldust-air mixtures in combustion turbines. It has beenobserved that the combustion of the mixture in the combustion chambermay be initiated by means of an electric spark, ration could not beattained as the combustion is in such case a very slow one, so that onlylow speeds could be obtained which were insuflicient to make thearrangement practical.

I have found that the rotational speed of the turbine can be raised tothe point necessary to maintain the continuous operation of the same ifa coal-dust-air mixture is introduced into the turbine under conditionswhich will efi'ect self-ignition. I have found that self-ignition of thefuel mixture is promoted by certain arrangements of parts in thecombustion space which are at a higher'temperature than the surroundingarts, and that thereby a satisfactory regu arity and constancy in theself-ignition of the periodically charged mixture can be obtained. Theparts which are to be kept at a higher temperature than theirsurroundings (the latter'term is to be understood to mean all the wallsand parts which bound the combustion space) may, for example, beuncooled while the surrounding elements may be cooled, or these parts.may be inserted Within the bordering Walls of the combustion chamber asseparate pieces so that the air space, which is present even when thefitting is exact, prevents the 837,084, and in Germany Il'ebruary 15,1828.

flow of heat from these parts 'to the adjoining cooler elements of thecombustion chamber. These parts may also be separately heated in themanner of incandescent heads, glowin spirals, etc. I

11 order to insure correct adjustment and proper control of the momentof ignition, I arrange suitable materials in the combustion space atsuch places that during the operation of the explosion chambers theyassume a temperature suflicient to cause ignition of the fuel and-airmixtures, such materials having possibly also a catal ic action whichfavors rapid and comp ete combustion. Such materials are most suitablylocated in the neighborhood of those parts of the combustion chamber atwhich self-ignition, as experience has shown, is most favored or isinitiated-experiments with piston explosion engines have shown thatself-ignition does not proceed from the center of the body of gas-andmay be advantageously supported 'upon catch surfaces of all kinds orintroduced into roughenin grooves, undercuttings and so forth, in t oseparts of the combustion chamber which are at a higher temperature thantheir surroundings. I have determined that particularly those bodiesserve as efiicient igniting bodies which possess very large superficialarea'in a small volume of material. I have found that substances such asfinely divided ashes or slag, which have a large superficial area for aunit of volume and are incombustible, possess the necessary action andare, moreover, not difficult to make. As the fine coal dust of the coaldust and air mixture exploded in the combustion chamber on combustionproduces extremely small ash and slag particles,

bastion chamber at which the igniting mate- I rial is able to exert itsaction most favorably, and particularly those parts which are or can bemaintained at a higher temperature than their surroundings, with devicessuch as Patented Apr. 4, I933 UNITED ST TES PATENT OFFICE HOLZWABTH, OI"DUSSELDORi' GERMANY, ASSIGNOB '10 HOLZWABTE GAB TURBINE 00., OF SANFRANCISCO, CALIFORNIA, A CORPORATION OI DELAWARE EXPLOSION TUBIBINEApplication filed February 5, 1929, Serial No.

by means of coal dust, and more particularly for effecting self-ignitionof a coal dust and air mixture in the explosion chambers of suchturbine.

Among the known internal combustion en-, gines designed to employ coaldust as a fuel, those which efi'ect ignition of the fuel in a mannersimilar to the Diesel process, that is, by injectin the coal dust into abody of hot compressed air in the combustion chamber, appear to have ledto the first practical success; on the other hand, ordinary pistonengines have not yet'been operated successfully with coal dust and airunder self-ignition of the mixture. Many attempts have been made toeffect the combustion of coaldust-air mixtures in combustion turbines.It has been observed that the combustion of the mixture in thecombustion chamber may be initiated by means of an electric spark, but acontinuous turbine o ration could not be attained as the combustion isin such case a very slow one, so that only low speeds could be obtainedwhich were insuflicient to make the arrangement practical. v

I have found that the rotational speed of the turbine can be raised tothe point necessary to maintain the continuous operation of the same ifa coal-dust-air mixture is introduced into the turbine under conditionswhich will eifect self-ignition. I have found that self-ignition of thefuel mixture is promoted by certain arrangements of parts in thecombustion space which are at a highertemperature than the surroundingparts, and that thereby a satisfactory regu arity and constancy in theself-ignition of the periodically charged mixture can be obtained. Theparts which are to be kept at a higher temperature than theirsurroundings (the latter'term is to be understood to mean all the wallsand parts which bound the combustion space) may, for example, beuncooled while the surrounding elements may be cooled, or these partsmay be inserted within the bordering walls of the combustion chamber asseparate pieces so that the air space, which is present even when thefitting is exact, prevents the 837,084, and in Germany Iebruary 15,1928.

flow of heat from these parts to the adjoining cooler elements of thecombustion chamber. These parts may also be separately heated in themanner of incandescent heads, glowin spirals, etc. I

n order to insure correct adjustment and proper control of the moment ofignition, I arrange suitable materials in the combustion space at suchplaces that during the opera tion of the explosion chambers they assumea temperature suflicient to cause ignition of the fuel and air mixtures,such materials having possibly also a catal ic action which favors rapidand comp ete combustion. Such materials are most suitably located in theneighborhood of those parts of the combustion chamber at whichself-ignition, as experience has shown, is most favored or isinitiated-experimen ts with piston explosion engines have shown thatself-ignition does not proceed from the center of the body of gasand maybe advantageously supported upon catch surfaces of all kinds or introduced into roughenin grooves, undercuttings and so forth, in t ose partsof the combustion chamber which are at a higher temperature than theirsurroundings. I have determined that particularly those bodies serve asefiicient igniting bodies which possess very large superficial areaiin asmall volume of material. I have found that substances such as finelydivided ashes or slag, which have a large superficial area for a unit ofvolume and are incombustible, possess the necessary action and are,moreover, not difficult to make. As the fine coal dust of the coal dustand air mixture exploded in the combustion chamber on combustionproduces extremely small ash and slag particles,

I provide measures whereby such ash and slag granules are caught anddeposited u on a suitable art of the combustion cham r, such granu esupon solidification producing a body of highly active igniting material.I accordingly provide those parts of the combustion chamber at which theigniting mate- I rial is able to exert its action most favorably, andparticularly those parts which are or can be maintained at a highertemperature than their surroundings, with devices such as catchsurfaces, grooves, rougheningp, undercuttings and so forth into which te ash or slag particles roduced by the combustion preci itate. e depositso produced durmg e operation 0 the turbine exerts a favorable influenceupon the initiation and the course of the combustion. In order that nounnecessarily large deposits may take place, the arts designed to carrythe same are prefera 1y arranged in those sections of the chamberwhereinthe gases flow with great violence so that the portion of the depositwhich is not positioned directly upon or only a short distance from thecatch surfaces, i. e. in the grooves, undercuttings and so forth, isblown or burnt away by the stream of combustion gas.

Instead of generating the igniter deposit I from the operating coal dustused to generate the combustion gases employed to operate the turbinerotor, the same may be produced by means of an auxiliary and separatecombustible coal dust and air mixture which is blown against the 'hotart or parts of the combustion chamber ad zipted to receive the same.The coal dust in this mixture is preferably more finely divided thanthat of the o crating mixture and also richer in volati, e matter. Thisauxiliary mixture, after the body of igniting material has beendeposited, may be employed, if desired, to ignite the operating mixturein the combustion chamber. To this end, jets of such auxiliarymixturerare directed at predetermined moments against theigniter-carryin surface and self-ignited on contact with suc igniter,the flame so produced causing explomom or rapid combustion of the chargein the combustion chamber. In this way the advanta e is obtained that bycontrolling the auxi iary mixture completely independently of theoperating coal-dust-air mixture, sharply defined self-ignitions of theperiodic charges of such operatin mixtures can be obtained atarbitrarily a justable moments.

If no artificially produced igniters (i. e. produced outside thecombustion chamber and manually positioned therein) are disposed in thecombustion chamber, but instead only the conditions are observed whichfavor the formation of the igniter out of the operating or auxiliarycombustible mixtures as by suitable arrangement of hot elements of thecombustion chamber which are formed to receive a deposit of ignitingmaterial and trates b way of example several embodiments of m invention,and particularly of the heated e ements located in the combustion space,Fig. 1 shows diagrammatically a partial section through a turbinecombustion chamber and nozzle valve; Fig. 2 illustrates an enlargedsection of the nozzle valve head shown in Fig. 1; Fig. 3 is a partiallon tudinal section through an explosion tur ine provided with a nozzlevalve of the iston type, and Fig. 4 is an enlarged detail of ig. 3.

F i 1 shows an explosion chamber a provide with the usual jackets forcooling the same. Valves b are arranged at the inlet end of thecombustion chamber and are adapted to be controlled in well-known mannerto charge the several operating media, such as scavenging air, chargingair, operating fuel, starting fuel, etc., eriodically and in propersequence. A nozz e valve 0 controls the communication between theinterior of the combustion chamber a and the nozzle channel d, whichlatter conducts the explosion (gases to a nozzle e disposed opposite thebla es of the turbine rotor 7 located in the tur ine housing It. Thehead or plate 0 of the nozzle valve 0 is located in the path of thecombustion gases as they stream out of the combustion chamber into thechannel (1 upon opening of the valve. This valve head is consequentlyexposed to very hot gases during the operation of the turbine, andunless specially cooled reaches a temperature above that of thesurrounding parts of the combustion chamber. The cooling of this valvehead is, however, difiicult and cooling arrangements therefor are rathercom licated.

In accordance with tiie present invention, the cooling of the nozzlevalve head is omitted and the same thus permitted to attain atemperature higher than that of its surroundings. This element isadvantageously located for such purpose because of the fact that it ispositioned at a point at which the combustion gases flow very rapidlyand is therefore struck most violently by such gases.

As indicated above, ash and slag, such as are deposited by an explodedmixture of coal dust and air, when heated to a high temperature, arecapable of causing self-ignition of combustible mixtures of coal dustand air, such deposit of ash and slag having a large surface area perunit volume and probably aiding catalytically the combustion of the fueland air. I have found that the face of the nozzle valve head which isstruck by the stream of combustion gases as they issue from theexplosion chamber is highly ada ted to support a mass of such ash andslag. 0 this end I may provide the face of the nozzle valve head withundercut surfaces 0, as shown at the right of Fig. 2, which provide asuitable clinging surface for a layer of igniter material 2' produced inany desired manner. The bottom face of the valve head may,

